Epic Goal

• Update the scale from zero autoscaling annotations on MachineSets to conform with the upstream keys, while also continuing to accept the openshift specific keys that we have been using.

Why is this important?

• This change makes our implementation of the cluster autoscaler conform to the API that is described in the upstream community. This reduces the mental overhead for someone that knows kubernetes but is new to openshift.
• This change also reduces the maintenance burden that we carry in the form of addition patches to the cluster autoscaler. By changing our controllers to understand the upstream annotations we are able to remove extra patches on our fork of the cluster autoscaler, making future maintenance easier and closer to the upstream source.

Scenarios

1. A user is debugging a cluster autoscaler issue by examining the related MachineSet objects, they see the scale from zero annotations and recognize them from the project documentation and from upstream discussions. The result is that the user is more easily able to find common issues and advice from the upstream community.
2. An openshift maintainer is updating the cluster autoscaler for a new version of kubernetes, because the openshift controllers understand the upstream annotations, the maintainer does not need to carry or modify a patch to support multiple varieties of annotation. This in turn makes the task of updating the autoscaler simpler and reduces burden on the maintainer.

Acceptance Criteria

• CI - MUST be running successfully with tests automated
• Release Technical Enablement - Provide necessary release enablement details and documents.
• Scale from zero autoscaling must continue to work with both the old openshift annotations and the newer upstream annotations.

Dependencies (internal and external)

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Previous Work (Optional):

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Open questions::

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Done Checklist

• CI - CI is running, tests are automated and merged.
• Release Enablement <link to Feature Enablement Presentation>
• DEV - OpenShift code and tests merged: <link to meaningful PR or GitHub Issue>
• DEV - OpenShift documentation merged: <link to meaningful PR or GitHub Issue>
• DEV - OpenShift build attached to advisory: <link to errata>
• QE - Test plans in Polarion: <link or reference to Polarion>
• QE - Automated tests merged: <link or reference to automated tests>
• DOC - OpenShift documentation merged: <link to meaningful PR>

please note, the changes described by this epic will happen in OpenShift controllers and as such there is no "upstream" relationship in the same sense as the Kubernetes-based controllers.